Fire & Drought
Test wildlife, Too

Game Range Articles
by Mike Thompson,
FW&P wildlife biologist,
writing for the Pathfinder

August 17, 2000
Seeley Swan Pathfinder
Seeley Lake, Montana

by Mike Thompson,

Fires burning over many thousands of acres this summer are
reshaping and redefining wildlife habitat on a scale seldom witnessed
during the previous 80 years in western Montana.

And, the extreme heat we've experienced since mid-July, as
well as ever-worsening drought conditions that set in over a year
ago, have added a weather stress that affects us all.

What about our wildlife?

Certainly, fire and drought are natural and not too uncommon
occurrences that native wildlife species are evolutionarily adapted
to cope with, just like deep snow and cold temperatures. But,
like snow and cold, it is reasonable to expect that drought and
heat can severely stress individual animals and test their genetic
fitness.

It's not pretty, but that's how wild species and populations
adapt to their environment. By being tested under occasionally
extreme conditions. And, by naturally culling those individuals
that are proven unfit to pass on their genes. In this way, the
surviving population, although sometimes temporarily reduced in
number, emerges stronger in the long run.

So, is this the introduction to an article predicting gloom
and doom for wildlife?

Not yet. But, what are the risk factors?

Perhaps the most obvious risk factor today is a flaming forest.
Back in 1988, when the Canyon Creek fire was burning through the
Scapegoat Wilderness and beyond, Montana Fish, Wildlife &
Parks (FWP) was fortunate enough to have some radioed elk in the
path of the fire. So, we can offer a bit of insight on how elk
react when their habitat is burning. I quote from a 1988 progress
report by Mark Hurley, who was the graduate student working on
the elk study at that time:

"The Canyon Creek fire in the Scapegoat Wilderness did
not cause any significant movements of elk in the area. The elk
seemed to move just far enough to be out of the path of the fire.
Elk were observed within 1 kilometer (0.6 mile) of flames several
times."

At the opposite end of the wildlife spectrum from large, mobile
elk are reptiles and amphibians. The moist, permeable skin of
amphibians would seem to elevate their vulnerability to heat and
drying. But, a literature review published in the Summer 1999
issue of Wildlife Society Bulletin indicates that, "Overall,
amphibians and reptiles did not appear to be disturbed by approaching
fire and responded in adaptive manners that minimized mortality.
For example, large breeding choruses of frogs have been observed
in wet areas immediately after fires, surrounded by still-smoking
ashes."

Although research was conducted in a vastly different environment
than ours, the same Bulletin article presents an interesting
observation on rattlesnakes: "Means and Campbell (1981) examined
effects of prescribed burning on a population of eastern diamondback
rattlesnakes in Florida. Of 68 individual rattlesnakes marked
and captured in a forest subjected to 5 prescribed fires in as
many years, only 2 snakes were killed by burning. Both snakes
were shedding their skin, which may have hampered their sensory
perception and consequently their ability to detect and disperse
away from approaching fires."

Common sense dictates that native animals are well adapted
to escape a flame, unless individuals become trapped in some way
or simply run out of luck. But, how do they handle day after day
of unusually intense heat?

Recent research from eastern Oregon suggests that elk can withstand
many days of summer temperatures in excess of 77 degrees, without
access to any shade, and still gain as much weight on the same
diet as elk with unlimited access to shade.

But, this summer we're talking about prolonged periods with
temperatures in the 90's and higher. There is speculation and
limited evidence in the scientific literature that such high temperatures
cause elk to increase their metabolismburn more energyto cool
themselves under extended periods of intense heat. Basically,
elk sweat, but they do so at a cost of increased energy loss.
They also may decrease food intake, which may be an added stress
to nursing females and their young calves.

Then again, there's the example of a well studied, wild elk
population that colonized a semi-desert region of southern Washington
a few years back. This population of elk increased at a remarkably
high rate, despite enduring conditions every summer that would
be comparable to or worse than those we're experiencing this year.

Perhaps more important to elk than the heat itself is access
to water and good food. If both are available, elk can be expected
to handle heat stress without measurable effects on calf production
or survival. And, it's surprising how long elk forage can retain
its green, succulent quality under a thick forest canopy next
to a seep or spring, even in this searing heat. However, vegetation
started drying out unusually early this summer, and if the drying
persists late into the fall, we may see some lowered calf counts
in the next year or two.

The bottom line? Our wildlife is almost certainly handling
this extreme summer weather a lot better than we are. But, that's
not to say there isn't a little more stress than usual in the
wilds. I would say that weather patterns this coming fall, winter
and spring will have a much greater potential effect on wildlife
than the weather we've experienced so far.

So, it's wait and see.

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